Diggins is a member of the U.S. women's cross-country skiing team, which is favored to win a medal at the Pyeongchang Olympics. It would be only the second medal in the sport for the United States and the first for the women's team.

Before Diggins was an Olympic skier, before she had even taken her first steps, her parents strapped her into a baby carrier and took her cross-country skiing near her hometown, Afton, Minnesota. But she worries that future generations of American children might miss that opportunity.

The risk is real. In the United States, the average time between the last frost of the spring and the first of the winter has expanded by 10 days since the first half of the 20th century.

Winter is shrinking in places like Hayward, Wisconsin, a town of 2,300 that swells to more than 12,000 people in late February during the American Birkebeiner, North America's largest cross-country ski race. Last year, organizers canceled the event for lack of snow.

A new analysis by the Rhodium Group's Climate Impact Lab suggests that popular ski resort towns in the United States will lose huge portions of their ski seasons by century's end. If global greenhouse gas emissions continue to rise, the report predicts, the Lake Tahoe area will experience subfreezing temperatures only eight days a year by 2100, 80 percent fewer than the average from 1981 to 2010. Ski season would be essentially dead.

So, Diggins and other winter sport athletes are becoming advocates for climate action. I interviewed her just before her World Cup win last month to learn more about why she thinks winter is worth protecting. (The following has been edited and condensed.)

Cross country skiers Sadie Bjornsen and Jessica Diggins of the U.S. celebrate at the FIS Nordic Ski World Championships on Feb. 26, 2017, in Lahti, Finland. (Kai Pfaffenbach / Reuters file)

Q: Why are you speaking up about climate change?

A: Growing up, I didn't play video games. I didn't watch TV. I went and played in the snow. I built snow forts and snowmen, I went sledding with my friends, and I went cross-country skiing every single weekend with my family and my friends. I don't want my kids to grow up in a world where they've never experienced snow because we weren't responsible enough.

Q: Why do you think you're qualified to speak up?

A: One reason I feel that I can say how much climate change is affecting us is because I've seen it all over the world. This isn't just like, "Oh, winter in Minnesota has been hard for the last 10 years." This is like, nope, it's people I've spoken to in Switzerland who are losing their jobs because winter's going away. And I've seen it in France: They had to pull ice from the lake in order to make a ski course up in the mountains where they've never had problems with snow.

Q: How is climate change affecting your sport?

A: As a kid, it was never hard to find trails to ski on, and now over the last 10 years it has been so hard to be able to ski on real snow. Most venues over the last three years have been exclusively on man-made snow. The same World Cup courses that we race get more and more dangerous with man-made snow because it gets icy. One of my teammates broke his leg on a corner of a course where it never should have been as fast as it was. Real snow, it feels softer. It's not as hard when you fall, and having actual snow on the trees and on the ground outside of the racecourse is more beautiful.

Q: What about people who say that fighting climate change is going to hurt the economy?

A: You can look at different solutions for the economy, but you only get one earth to live on, and you have to breathe the air that is on this earth. We have to do it in a way that doesn't hurt families economically, which is why I'm supporting the carbon fee and dividend solution, because it puts a fee on carbon and returns the revenue to households.

Q: What's one thing you want people to know about the experience of cross-country skiing?

A: You know, when people try skiing for the first time they always call me up and go, "That is so fun. I didn't know how fun it could be." You use your body to push yourself, and you get to see views that you never would see otherwise. There are trails that go up and around the mountains, and you're skiing down these switchbacks and you're skiing up them, and you get to see the world from a very different point of view. It's very special. I think that that's something that definitely shouldn't be lost.